The satisfactory removal of soils/stains is a particular challenge to the formulator of a detergent composition for use in a washing process such as laundry or machine dishwashing process.
Traditionally, the removal of soils/stains has been achieved by the use of bleach components and also by enzyme components.
Amylases are known as effective soil/stain removal agents, for example, in the removal of starch stains such as chocolate.
Polymeric polycarboxylic acid components are also known in detergent compositions as effective soil suspension and anti-encrustation agents.
Chelating agents are known in detergent compositions for their ability to assists in the removal of organic stains during the laundry process.
Phosphorus containing compounds such as sodium tripolyphosphate have effective builder properties; however environmental concerns have made the use of phosphorus containing compounds less attractive in detergent compositions.
A problem encountered with the use of enzymes as components of detergents is that enzyme activity in the wash may be affected by the presence of other detergent components in the wash solution.
A problem encountered with the use of high level of polymeric polycarboxylic acid compounds when in presence of high level of an alkaline source is the propensity of these polycarboxylic compounds to lead to an overbuilt situation which may impair the amylase activity and then leads to poor soil/stain removal performance. Furthermore, high levels of polymeric polycarboxylic acid compounds increase the cost of the detergents to the consumer. On the other hand, low levels of polymeric polycarboxylic acid compounds may lead to encrustation, especially when using high levels of carbonate/silicate alkalinity in a non phosphate builder-containing detergent composition.
The detergent formulator thus faces the challenge of formulating an environmentally friendly product which maximises soil/stain removal, which minimises the occurence of any unwelcome encrustation, which avoids degradation of the detergent components and which is also inexpensive.
U.S. Pat. No. 4,919,845 discloses a phosphate free detergent composition comprising a polycarboxylate compound and a hydroxy-ethylene 1,1 diphosphonate (HEDP) chelant. Particularly disclosed are high levels of polycarboxylates 3% to 4% by weight, 0.22% to 0.4% by weight of HEDP, 12.5% by weight of an alkalinity source and 0.5% by weight of an enzyme granulate. The described composition is asserted to provide effective antiencrustation benefits.
The Applicants have found that the occurence of encrustation effects arising from use of polymeric polycarboxylic compounds at low levels are related to the level of alkalinity present into the wash solution, the alkalinity being produced by the alkaline components of the composition. A high level of an alkalinity source in the detergent composition tends to exarcerbate the encrustation problem, as does a high level in the wash solution. Whilst reducing the level of alkalinity employed in the wash tends to ameliorate these problems; this is accompanied by a marked negative effect on the stain/soil removal ability.
The Applicants have now surprisingly found that where a non phosphate builder-containing detergent composition containing a surfactant, a water-soluble organic polymeric polycarboxylic compound, a chelant and an amylase together with an alkalinity source is employed, an enhanced stain/soil removal and a reduced encrustation may be obtained.
The Applicants have found that the further addition of compounds enhances the overall soil/stain removal performance. Such additional compounds may be selected from proteases, a source of hydrogen peroxide with or without peroxyacid bleach precursors and mixtures thereof.
It is therefore an object of the present invention to provide compositions suitable for use in laundry and machine dishwashing methods producing enhanced stain removal.
It is a further object of the invention to provide compositions for use in laundry and machine dishwashing methods wherein said compositions show less propensity to cause encrustation.